the big problem i see is they dont include an ejector block and you cant use the one from your parts set as it is an NFA specific part and has a cutout for the full auto trip. I assume they will be making the ejector block also and dsa probably stocks them but will def add to the price

I never thought the full auto type FAL ejector block was a NFA item. The no-no is to cut the upper receiver to accept the auto (safety) sear on the pin block w/o proper liscensing. Some early Imbel FAL receivers were imported with the full auto ejector block installed but the receiver was not cut to accept the sear. This is the way I've understood it unless I'm either wrong or implementation of the regs have changes since then.

I bought , and had to return, a couple of Imbel rec in the late 80's from dealer wharehouse that came with FA ejector blocks installed. I was told that they had to be replaced with semi ejector blocks. I do not know for fact that this is an issue but i cant imagine that dealer wharehouse went to the trouble unless prompted to do so by ATF. I do know the rec where not cut for the trip on the hinge pin but the window for the lever was visible in the block and the replacement rec didnt have the cutout visible in the ejector block.
I would think that as cheap as century is they would be using the FA ejector block in their FAL and l1a1 builds if it was legal to do so

here is what ATF says on the matter, notice it says it could meet the definition of a machine gun or "might" not

DEPARTMENT OF THE TREASURY
BUREAU OF ALCOHOL, TOBACCO AND FIREARMS
WASHINGTON, DC 20226

MAR 20 2000

903050:CHB
3311

Dear Mr. Bardwell:

This refers to your letter of February 17, 2000, in which you asked
if ATF would consider an FAL rifle assembled with a U.S. made
receiver and an FAL machinegun ejector block to be a machinegun.

The term "machinegun" is defined in section 5845(b) of the National
Firearms Act. An FAL style rifle with a machinegun style ejector
block could meet the definition of a machinegun, or it might not
meet the definition of machinegun. If the rifle was capable of
firing automatically, it would be a machinegun regardless of the
style of ejector block used.

We trust that the foregoing has been responsive to your inquiry.
If you have further questions concerning this matter, please
contact us.

I'm not trying to argue the point either way, but sometimes a distributor will go above and beyond the letter of the law (or regulations) to be above any possible legal challenge or change of implementation of the statutes. One example that comes to mind is the change in demill processes that does/does not leave the stamped receiver bits still attached for AK kits. As far as I know this was not a reaction to a change in BATF regulations but done to ensure no doubt or question as to compliance to those regulations. Failure to do so might potentially put the entire imported shipment under BATF impound or seizure. It could be considered cheap insurance that the kits will not be confiscated as contriband. As to Century installing semi blocks, it is probably cheaper and therefore more cost effective to drill and pin new semi blocks instead of trying to retrofit used FA ejector blocks.

After all that is said and done, bottom line is I don't know for sure.

Edit; Just read the ATF letter you posted. Good information. Makes me believe that the semi ejectors are installed as an insurance measure of compliance.

good point on century not reusing them, hadnt thought of the fitting issue.

Looking the letter from ATF over it does appear that they didnt say it would be in violation, If I read the letter correctly it seems it would indeed be OK to use the fa ejector block as long as the rifle was only cabaple of firing one shot per pull of the trigger. I think for safeties sake if i were reusing an FA ejector block i would weld up the window the trip lever passes thru.